1. Field of the Invention
The present invention generally relates to the field of inspection and analysis of specimens. More particularly, the present application relates to characterizing thin films in semiconductor integrated circuits.
2. Description of Related Art
Thin film layers are widely used in semiconductor devices. In one example, a thin film barrier layer is used to prevent copper from migrating into an insulator. However, a variety of factors cause uneven thickness and composition in thin film layers and prevent thin films from effectively performing their functions. Defects can ultimately lead to failure of integrated circuits.
Consequently, it is desirable to provide improved techniques and systems for measuring thin films that more effectively characterize thin film layers in a variety of semiconductor devices.
Methods and apparatus are provided for characterizing thin films in an integrated circuit device. A target including multiple layers is scanned using an x-ray emission inducer. X-ray emissions characteristic of materials in the target are measured. In one example, multiple beam energies are used to conduct the scan. In another example, continuously varying beam energies are used. Information such as K-ratios or the intensity of the x-ray emissions is provided to determine the thickness and/or composition of layers in the scan target.
According to various embodiments, a method for characterizing thin films is provided. A first scan target in an integrated circuit device is scanned by using a particle beam generator configured to emit particles at a first energy. The particles interact with a first layer comprising a first material and a second layer comprising a second material in the scan target. The second layer lies beneath a first layer. X-ray emissions associated with scanning at the first energy are detected. The first scan target is scanned by using the particle beam generator configured to emit particles at a second energy. The particles interact with the first layer comprising the first material and the second layer comprising the second material in the scan target. X-ray emissions associated with scanning at the second energy are detected. The second layer is characterized by using x-ray emissions from the first and second materials resulting from scans at the first and second energies.
According to other embodiments, an apparatus for measuring thin films is provided. The apparatus includes and x-ray emission inducer and an x-ray emission detector. The x-ray emission inducer is operable to scan a first scan target in an integrated circuit device at a first energy and a second energy. The x-ray emission inducer causes x-ray emissions from a first layer comprising a first material and a second layer comprising a second material in the scan target. The x-ray emission detector is operable to measure characteristic x-ray emissions resulting from the scan at the first energy and the second energy. The x-ray emissions are characteristic of the first and second materials scanned at the first energy and the second energy are measured to characterize the second layer.
According to still other embodiments, a method for measuring thin films is provided. A first scan target in an integrated circuit device is scanned by using an x-ray emission inducer configured to scan at energies continuously varying between a first and a second energy. The scan target includes a first layer comprising a first material and a second layer comprising a second material. X-ray emissions associated with scanning at energies continuously varying between the first and second energies are detected. The x-ray emissions detected include emissions characteristic of the first and second materials used to determine the thickness and composition of the second layer.
In some embodiments, both a first and second layer are characterized. Characterization can include determining the thickness and composition of the various layers.
These and other features and advantages of the present invention will be presented in more detail in the following specification of the invention and the accompanying figures which illustrate by way of example various principles of the invention.